In the past, feedback coils have been wound on the coil mandrels of speakers and have been used to apply degenerative feedback in an audio amplifier driving the speaker as disclosed in U.S. Pat. No. 3,530,244 which issued to M. G. Reiffin on Sept. 22, 1970, for "Motional Feedback Amplifier Systems." However, such feedback has not proven to be commercially successful because it does not remedy the basic defects in the lower frequency response of the speaker.